Their nest is on the ground near water and about a metre across.
Unlike many other ducks and geese the male helps with the nest construction.
Average egg size (for the mute swan) is 113×74 mm, weighing 340 g, in a clutch size of 4 to 7, and an incubation period of 34–45 days.
[10] With the exception of the whistling ducks they are the only anatids where the males aid in incubating the eggs.